Back support adjustment for torsion chair



Dec. 21, 1965 P. c. WELCH ET AL 3,224,807

BACK SUPPORT ADJUSTMENT FOR TORSION CHAIR Filed July 19, 1965 2Sheets-Sheet 1 Dec. 21, 1965 P. c. WELCH ETAL 3,224,807

BACK SUPPORT ADJUSTMENT FOR TORSION CHAIR Filed July 19, 1963 2Sheets-Sheet 2 INVENTORS P 664/6 A/A'ZC'K/ Fm A/ MAfZ United StatesPatent Oflice 3,224,807 Patented Dec. 21, 1965 3,224,807 BACK SUPPORTADJUSTMENT FOR TORSION CHAIR Phillip Craig Welch, East Grand Rapids, andRoy W.

Matz, Clarksville, Mich., assignors to Stcelcase, Iuc.,

Grand Rapids, Mich, a corporation of Michigan Filed July 19, 1963, Ser.No. 296,294 3 Claims. (Cl. 27--304) This invention relates to torsionmounted chair backs, and more particularly to a chair having a torsionmounted back having a horizontal, straight-line, front to backadjustment capacity.

Some ofiice chairs having a back mounted on a torsion bar for limitedresilience employ a back adjusting mechanism. This mechanismconventionally provides adjustment in a tilting manner, i.e. on aarcuate path. The mechanism is expensive and complex, including memberswith arcuate adjustment slots, interconnecting pins, tension springs,control knobs, stop knobs and linkages. Consequently, if the torsionmounted chair back is to be adjustable, the cost of the chair isnormally substantially increased.

The inventors herein, desiring to produce an adjustable torsion mountedchair back, discovered that with this type of mounting, the importantdirection of adjust-ment of the back is actually horizontal, forwardlyand rearwardly. Adequate arcuate action is achieved with the torsionmounting. Vertical adjustment can be easily achieved by movement of theback pad on the back support. Therefore, all the necessary adjustmentsare readily obtained. In pursuance of this discovery, the inventorsherein invented a unique, extremely simple and inexpensive adjustingmechanism to achieve a straight line, horizontal adjustment of atorsionally mounted chair back.

It is therefore an object of this invention to provide a novelhorizontally adjustable torsion back chair having a simplifiedinexpensive construction enabling simple adjustment, inexpensivemanufacture, requiring no spring, stop bars, linkages, etc., andcoopera-ble with the torsion mounting to effect a highly comfortablechair.

It is another object of this invention to provide this novelconstruction in a manner achieving excellent comfort without undueexpense.

These and other objects of this invention will become apparent uponstudying the following specification in conjunction with the drawings inwhich:

FIG. 1 is a perspective view of a torsion' mounted chair employing theinventive construction;

FIG. 2 is a perspective view of the novel chair frame employing thenovel construction;

FIG. 3 is an enlarged, fragmentary, perspective view of the bottom sideof the adjusting mechanism;

FIG. 4 is a sectional fragmentary enlarged view taken on plane IV--lV ofthe apparatus in FIG. 2;

FIG. 5 is a fragmentary, enlarged, plan View of the torsion mountingmechanism; and

FIG. 6 is a fragmentary, enlarged, perspective, exploded view of theadjusting mechanism.

Referring specifically to the drawings, the novel chair 10 includes aseat mounting frame 12 upon which a seat 14 is mounted, and a resilient,back supporting, L-shaped spring 16 to which a back pad 18 is verticallyadjustably mounted.

The frame 12 includes a pair of oppositely positioned side portions 20and 22 resembling angle irons and having outwardly flared front portionsand inwardly converging rear portions for bolted attachment to seatbottom 14. Connecting these side portions, and extending transverselytherebetween, is a channel element 24 welded to elements 20 and 22. Apair of support ears 26 is severed from the bottom of channel 24 anddeformed upwardly to form a pair of generally parallel mounts (FIG. 5).Bearing sleeves of nylon or other suitable material 28 receiving thesquare torsion bar 30 are mounted in the ears. The ears verticallysupport the torsion bar while allowing rotation thereof. The bar isnonrotatively fixed to a support channel beam 32, and more specificallywith the side legs thereof, so that rotation of the beam twists the bar,since torsion bar 30 also has its ends affixed in side portions 20 and22 to form a nonrotative connection therewith.

The support channel 32 extends from front to rear between the sideelements 20 and 22, centrally of frame 12. It extends through an opening36 in one leg of channel 24 and through a slot 38 in the other leg.Channel support 32 is mounted and supported on and by torsion bar 30 byforming a non-rotative connection therewith. The mounts 26 thereforekeep the channel element 32 centered on the frame. This channel beam .32supports the chair back.

Secured around the center of the torsion rod 30 is an adjusting ear 42.This ear is twisted to have its outer end, i.e. opposite the endattached to the bar, in a plane displaced from the plane of its portionaround the bar. The outer end is in abutting contact with the upper endof a threaded adjusting stud 46 extending through the bottom of thefront end of channel 32, and including a knob 48. The ear is retained ina slot between a pair of fingers 49. By adjustment of knob 48 and screw46, the initial torsion imparted to bar 30 can be varied, to therebyvary the amount of torsion remaining in the bar to flex under a backload. This, therefore, controls the degree of resilience of the chairback.

Extending downwardly from the chair frame 12 is a screw mount shaft 50including a collar 52. The lower end of shaft 50 is inserted into a base54 having suitable legs 56.

Secured to the rear end of support channel 32 and around it is a secondchannel member 60 having a width or cross section greater than channel32 to cause the legs of the second channel 60 to overlap the legs ofchannel 32. This second channel is affixed to channel 32, as by welding,and the two attached channels provide what may be termed a channel meansincluding a channel section and a fiat member positioned parallelthereto. Suflicient clearance is provided between the bottoms of the twoattached channels to form a horizontal, rearwardly opening receivingslot 62 (FIG. 4).

The rearwardly directed opening of slot 62 slidably receives thehorizontal leg of an L-shaped, back-mounting, resilient spring bracket16 with sufiicient clearance (FIG. 3) to allow ready movement forwardlyand rearwardly of the spring and thus of the back pad 18 mountedthereon. This movement in a horizontal plane and on a straight line axisis controlled by a turn screw locking means comprising tightening ascrew 68 and knob 70. The screw portion 68 extends through an elongatedslot 66 extending forwardly and rearwardly in the bottom of secondchannel 60 (FIG. 3). The screw is in threaded engagement with thehorizontal leg of the L spring sup- .port 16. It extends through thesupport and against the bottom of channel 32. When this turn screw 68 isloosened, the leg of the back bracket may be moved forwardly orrearwardly to a desired adjusted position. The limits of this adjustmentare made by contact of the turn screw 68 with the ends of slot 66. Tolock the back in the adjusted position, the turn screw is tightened,causing its upper end to bear against the bottom of channel 32, andthereby force the horizontal leg of bracket 16 into bearing relationshipagainst the bottom of channel 60 to thereby lock the same together tosecure the L-shaped back member in a desired adjusted position. Theadjustment does not interfere in any way with the torsional resilienceof the back but rather is cooperative therewith to form a comfortablechair. Thus, there is produced a torsion back chair, with horizontalback adjustment employing a simple, but elfective construction enablingadjustable arcuate movement of the torsion back, and also enablinghorizontal adjustment of the back, yet at a relatively small cost ascontrasted to conventional constructions.

It is conceivable that certain minor obvious str-uctural changes couldbe made in the illustrated form of the invention, while incorporatingthe inventive principles taught. This invention is, therefore, not to belimited merely to the one preferred form of the invention depicted, butonly by the scope of the appended claims and the reasonably equivalentstructures tothose defined therein.

We claim:

1. An adjustable torsion back chair comprising in combination: a seatframe having a pair of interconnected opposite side portions; asubstantially rigid and inflexible support channel means positionedcentrally between said side portions and extending toward the back ofsaid frame; a torsion bar between said channel means and said sideportions; said torsion bar fixedly connected to said support channelmeans and to said side portions to support the said channel means andprovide limited torsional resilience thereto; said extending portion ofsaid channel means including a channel section and a substantially fiatparallel member defining together a rearwardly-opening horizontal slot;an L-shaped resilient back support having a lower leg portion; saidlower leg portion slidably engaged in said slot; an aperture formed insaid lower leg portion; at least one aperture formed in said channelmeans; at least one of said apertures having threads formed therein; atleast one of the unthreaded apertures being laterally elongated; andturn screw locking means passing through each of said apertures andengaging said threads; said locking means and elongated apertureproviding for position adjustment of said back support; and said lockingmeans when tightened in said threads urging said leg portion and channelmeans into bearing relationship'to thereby lock the same together tosecure said back portion in a desired adjusted position.

2. An adjustable torsion back chair comprising in combination: a seatframe having a pair of interconnected opposite side portions; asubstantially rigid and inflexible support channel positioned centrallybetween said side portions and extending toward the back of said frame;a torsion bar between said channel and said side portions; said torsionbar fixedly connected to said s-upport channel and to said side portionsto support the said channel and provide limited torsional resiliencethereto; a second channel member interfitted with and secured to thesaid extending portion of said support channel to define therewith arearwardly opening horizontal slot; an L-shaped resilient back supporthaving a lower leg portion; said lower leg portion slidably engaged insaid slot; an aperture formed in said lower leg portion; an apertureformed in the lowermost one of said slot-defining channels; one of saidapertures having threads formed therein; the unthreaded one of saidapertures being laterally elongated; and turn screw locking meanspassing through each of said apertures and engaging said threads; saidlocking means and elongated aperture providing for position adjustmentof said back support; and said locking means when tightened in I saidthreads urging said leg portion and one of said channels into bearingrelationship to thereby lock the same together to secure said backportion in a desired adjusted position.

3. An adjustable torsion back chair comprising in combination: a seatframe having a pair of interconnected opposite side portions; asubstantially rigid and inflexible support channel positioned centrallybetween said side portions and extending toward the back of said frame;a torsion bar between said channel and said side portions; said torsionbar fixedly connected to said support channel and to said side portionsto support the said channel and provide limited torsional resiliencethereto; a second channel member larger in cross-section than saidsupport channel interfitted beneath the said extending portion of thelatter and fixedly secured thereto to define therewith a rearwardlyopening horizontal slot; an L- shaped resilient back support having alower leg portion; said lower leg portion slidably engaged in said slot;a threaded aperture formed in said lower leg portion; an elongatedaperture formed in said second channel; and turn screw locking meanspassing through each of said apertures and engaging said threads; saidlocking means and elongated aperture providing for position adjustmentof said back support; and said locking means when tightened in saidthreads drawing said leg portion and second channel member into bearingrelationship to thereby lock the same together to secure said backportion in a desired adjusted position.

References Cited by the Examiner UNITED STATES PATENTS FRANK B. SHERRY,Primary Examiner.

3. AN ADJUSTABLE TORSION BACK CHAIR COMPRISING IN COMBINATION: A SEATFRAME HAVING A PAIR OF INTERCONNECTED OPPOSITE SIDE PORTIONS; ASUBSTANTIALLY RIGID AN INFLEXIBLE SUPPORT CHANNEL POSITIONED CENTRALLYBETWEEN SAID SIDE PORTIONS AND EXTENDING TOWARD THE BACK OF SAID FRAME;A TORSION BAR BETWEEN SAID CHANNEL AND SAID SIDE PORTIONS; SAID TORSIONBAR FIXEDLY CONNECTED TO SAID SUPPORT CHANNEL AND TO SAID SIDE PORTIONSTO SUPPORT THE SAID CHANNEL AND PROVIDE LIMITED TORSIONAL RESILIENCETHERETO; A SECOND CHANNEL MEMBER LARGER IN CROSS-SECTION THAN SAIDSUPPORT CHANNEL INTERFITTED BENEATH THE SAID EXTENDING PORTION OF THELATTER AND FIXEDLY SECURED THERETO TO DEFINE THEREWITH A REARWARDLYOPENING HORIZONTAL SLOT; AN LSHAPED RESILIENT BACK SUPPORT HAVING ALOWER LEG PORTION; SAID LOWER LEG PORTION SLIDABLY ENGAGED IN SAID SLOT;A THREADED APERTURE FORMED IN SAID LOWER LEG PORTION; AN ELONGATEDAPERTURE FORMED IN SAID SECOND CHANNEL; AND TURN SCREW LOCKING MEANSPASSING THROUGH EACH OF SAID APERTURES AND ENGAGING SAID THREADS; SAIDLOCKING MEANS AND ELONGATED APERTURE PROVIDING FOR POSITION ADJUSTMENTOF SAID BACK SUPPORT; AND SAID LOCKING MEANS WHEN TIGHTENED IN SAIDTHREADS DRAWING SAID LEG PORTION AND SECOND CHANNEL MEMBER INTO BEARINGRELATIONSHIP TO THEREBY LOCK THE SAME TOGETHER TO SECURE SAID BACKPORTION IN A DESIRED ADJUSTED POSITION.